Biological Potential of Polyphenols in the Context of Metabolic Syndrome: An Analysis of Studies on Animal Models

Metabolic syndrome (MetS) is a disease that has a complex etiology. It is defined as the co-occurrence of several pathophysiological disorders, including obesity, hyperglycemia, hypertension, and dyslipidemia. MetS is currently a severe problem in the public health care system. As its prevalence increases every year, it is now considered a global problem among adults and young populations. The treatment of choice comprises lifestyle changes based mainly on diet and physical activity. Therefore, researchers have been attempting to discover new substances that could help reduce or even reverse the symptoms when added to food. These attempts have resulted in numerous studies. Many of them have investigated the bioactive potential of polyphenols as a "possible remedy", stemming from their antioxidative and anti-inflammatory effects and properties normalizing carbohydrate and lipid metabolism. Polyphenols may be supportive in preventing or delaying the onset of MetS or its complications. Additionally, the consumption of food rich in polyphenols should be considered as a supplement for antidiabetic drugs. To ensure the relevance of the studies on polyphenols' properties, mechanisms of action, and potential human health benefits, researchers have used laboratory animals displaying pathophysiological changes specific to MetS. Polyphenols or their plant extracts were chosen according to the most advantageous mitigation of pathological changes in animal models best reflecting the components of MetS. The present paper comprises an overview of animal models of MetS, and promising polyphenolic compounds whose bioactive potential, effect on metabolic pathways, and supplementation-related benefits were analyzed based on in vivo animal models.

Serum adiponectin is a potential biomarker for metabolic syndrome in peri-and postmenopausal women

Metabolic syndrome (MetS) increases its prevalence during menopausal period and there is no appropriate marker for screening before the cardiovascular damage begun. This study aims to find the diagnostic accuracy and the appropriate cutoff level of serum adiponectin for the screening of MetS in peri- and postmenopausal women. Women aged at least 40 years old attending health checkup clinic were recruited. Anthropometric measurements, blood pressure, MENQOL, and blood chemistry (glucose, adiponectin, HDL-C, LDL-C, and TG) were recorded. MetS was defined by JIS 2009 criteria. 290 peri-and postmenopausal women mean age 54.25 ± 8.6 years were recruited. 66% was postmenopause and 21.4% of them has MetS. The socioeconomic and lifestyle factors seem similar among women with and without MetS. In the participants with MetS, the prevalence of abdominal obesity was higher (96.8% vs 49.6%, p < .001, respectively) and more prevalence of android fat distribution pattern was observed (76.2% vs 36%, p < .001, respectively). Serum adiponectin was significantly lower in women with MetS (6.0 ± 4.6 vs 9.2 ± 5.2 μg/mL, p < .001 in MetS and non-MetS, respectively). Serum adiponectin is a good biomarker for MetS and we recommend the cutoff level of serum adiponectin lower than 7.15 μg/mL for screening of MetS (AUC (95% CI) of = 0.72 (0.64-0.79), p < .001).

Cardiovascular consequences of metabolic syndrome

The metabolic syndrome (MetS) is defined as the concurrence of obesity-associated cardiovascular risk factors including abdominal obesity, impaired glucose tolerance, hypertriglyceridemia, decreased HDL cholesterol, and/or hypertension. Earlier conceptualizations of the MetS focused on insulin resistance as a core feature, and it is clearly coincident with the above list of features. Each component of the MetS is an independent risk factor for cardiovascular disease and the combination of these risk factors elevates rates and severity of cardiovascular disease, related to a spectrum of cardiovascular conditions including microvascular dysfunction, coronary atherosclerosis and calcification, cardiac dysfunction, myocardial infarction, and heart failure. While advances in understanding the etiology and consequences of this complex disorder have been made, the underlying pathophysiological mechanisms remain incompletely understood, and it is unclear how these concurrent risk factors conspire to produce the variety of obesity-associated adverse cardiovascular diseases. In this review, we highlight current knowledge regarding the pathophysiological consequences of obesity and the MetS on cardiovascular function and disease, including considerations of potential physiological and molecular mechanisms that may contribute to these adverse outcomes.

The adipose tissue and the involvement of the renin-angiotensin-aldosterone system in cardiometabolic syndrome

Cardiometabolic diseases are linked to a cluster of modifiable factors, including risk factors closely related to central adiposity. Chronic renin-angiotensin-aldosterone system (RAAS) activation has far-reaching effects on cardiometabolic risk and is a substantial contributor to this clinical condition. RAAS components are locally expressed in the vessels and adipose tissue. This review appoints RAAS, through the classical and the alternative view, as the main mediator of the cross-talk in cardiometabolic syndrome.

Protective effects of naringenin in cardiorenal syndrome

BACKGROUND

Cardiorenal syndrome is a complicated and bidirectional interrelationship between the heart and kidneys. Naringenin (NG) is a naturally occurring flavonoid possessing various biological and pharmacological properties.

MATERIALS AND METHODS

We tested whether NG could improve cardiac and renal function in a rat model of cardiorenal syndrome.

RESULTS

The results showed that NG-attenuated cardiac remodeling and cardiac dysfunction in rats with cardiorenal syndrome, as evidenced by decrease of left ventricle weight (LVW), increase of body weight (BW), decrease of LVW/BW, decrease of concentrations of serum creatinine, blood urea nitrogen, type-B natriuretic peptide, aldosterone, angiotensin (Ang) II, C-reactive protein, and urine protein, increase of left ventricular systolic pressure and falling rates of left ventricular pressure (dp/dtmax), and decrease of left ventricular diastolic pressure, left ventricular end-diastolic pressure, and -dp/dtmax. NG significantly inhibited the increase of lipid profiles including low-density lipoprotein, TC, and TG in rats. In addition, NG significantly inhibited the increase of cardiac expression of IL-1β, IL-6, and interferon γ. Moreover, NG decreased malonaldehyde level, increased superoxide dismutase activity and glutathione content in rats, and increased the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and catalytic subunit of γ-glutamylcysteine ligase (GCLc) in rats and Ang II-treated cardiac fibroblasts. Inhibition of Nrf2 and glutathione synthesis significantly suppressed NG-induced decrease of ROS level. Inhibition of Nrf2 markedly suppressed NG-induced increase of GCLc expression in Ang II-treated cardiac fibroblasts.

CONCLUSIONS

The data provide novel options for therapy of patients and new insights into the cardioprotective effects of NG in cardiorenal syndrome.

Olmesartan vs. ramipril in elderly hypertensive patients: review of data from two published randomized, double-blind studies

Hypertension is a frequent condition among individuals over 65 years of age worldwide and is one of the most important risk factors for cardiovascular (CV) disease. Effective drug treatment of elderly hypertensives is usually associated with a marked reduction in CV morbidity and mortality. Among the different classes of antihypertensive agents, angiotensin receptor blockers (ARBs) and ACE-inhibitors are supposed to provide the best efficacy in lowering blood pressure (BP) and protecting target organ damage while featuring a good tolerability profile. However, up to date, few randomized clinical studies have directly compared the activity and safety of ARBs and ACE-inhibitors in elderly hypertensive patients. Aim of this review of published and unpublished pooled data from two recent randomized, double-blind, controlled trials, is to offer a comprehensive head-to-head comparison of the antihypertensive efficacy of the ARB olmesartan medoxomil vs. the ACE-inhibitor ramipril in a large study population including more than 1,400 hypertensive subjects aged 65-89 years with mild-to-moderate essential hypertension. The efficacy of the two drugs was separately evaluated in subgroups of patients classified according to the presence of metabolic syndrome, reduced renal function, CV risk level, gender, class of age, type of arterial hypertension and previous antihypertensive treatments. Olmesartan showed a greater efficacy than ramipril both in terms of clinic BP reduction and rate normalization. Olmesartan appeared significantly superior to ramipril in providing a more homogeneous and long-lasting 24-h BP control and maintaining an effective antihypertensive action in the last 6-h period from drug intake. In subgroups of patients with additional clinical conditions, olmesartan gave comparable, and in some cases greater, BP responses than those achieved with the ACE-inhibitor. The incidence of adverse events was similar for both drugs. Olmesartan may thus represent an effective alternative to ACE-inhibitors among first-line drug treatments for hypertension in older people.

Antihypertensive efficacy and safety of olmesartan medoxomil and ramipril in elderly mild to moderate essential hypertensive patients with or without metabolic syndrome: a pooled post hoc analysis of two comparative trials

BACKGROUND

Two recent identically designed trials (one Italian and one European multinational) have compared the head-to-head efficacy and safety of the angiotensin II receptor blocker olmesartan medoxomil and the angiotensin converting enzyme inhibitor ramipril, in elderly patients with essential hypertension.

OBJECTIVE

The aim of the present study was to assess the antihypertensive efficacy of olmesartan and ramipril in elderly patients with hypertension, with or without metabolic syndrome, by performing a pooled analysis of data from the two head-to-head trials.

METHODS

After a 2-week, placebo wash-out, 1,453 treated or untreated elderly hypertensive patients aged 65-89 years [with sitting office diastolic blood pressure (DBP) 90-109 mmHg and/or sitting office systolic BP (SBP) 140-179 mmHg] were randomized to 12-weeks of double-blind treatment with olmesartan 10 mg or ramipril 2.5 mg once daily. Treatment could be up-titrated to 20 and 40 mg for olmesartan, and 5 and 10 mg for ramipril, after the first 2 and 6 weeks, respectively, in patients with inadequately controlled BP (BP ≥ 140/90 mmHg for non-diabetics and ≥ 130/80 mmHg for diabetics). Office BP was measured at randomization and after 2, 6 and 12 weeks of treatment. 24-h ambulatory BP recordings were obtained at randomization and after 12 weeks.

RESULTS

Of the 1,426 patients in the intent-to-treat analysis, 735 (51.5 %) had metabolic syndrome (olmesartan, n = 372; ramipril, n = 363). After 12 weeks of treatment, baseline-adjusted office BP reductions were greater (p < 0.05) with olmesartan (SBP 17.0 mmHg; 95% CI 18.4, 15.6; DBP 9.6 mmHg; 95% CI 10.4, 8.8) than with ramipril (SBP 14.7 mmHg; 95% CI 16.1, 13.2; DBP 8.4 mmHg; 95% CI 9.2, 7.6) in patients with metabolic syndrome. In these patients, BP normalization rates were also greater with olmesartan than with ramipril (46.0 vs. 35.8%, p < 0.01). Similarly, in patients without metabolic syndrome, the antihypertensive efficacy of olmesartan was also significantly (p < 0.05) better than that of ramipril. In the subgroup of patients with valid ambulatory BP (ABP) recordings and metabolic syndrome (olmesartan, n = 182; ramipril, n = 170), the reduction in mean 24-h ABP was greater with olmesartan (SBP 10.2 mmHg; 95% CI 11.8, 8.6; DBP 6.6 mmHg; 95% CI 7.5, 5.6) than with ramipril (SBP 8.5 mmHg; 95% CI 10.2, 6.9; DBP 4.7 mmHg; 95% CI 5.7, 3.7), with a statistically significant (p < 0.01) difference for the DBP comparison. The proportion of patients experiencing drug-related adverse events was comparable in patients with (olmesartan 2.4 % vs. ramipril 2.8 %) and without (3.5 vs. 3.7 %) metabolic syndrome.

CONCLUSIONS

Olmesartan provides more effective BP control than ramipril in elderly hypertensive patients with and without metabolic syndrome.

Heart of the matter: coronary dysfunction in metabolic syndrome

Metabolic syndrome (MetS) is a collection of risk factors including obesity, dyslipidemia, insulin resistance/impaired glucose tolerance, and/or hypertension. The incidence of obesity has reached pandemic levels, as ~20-30% of adults in most developed countries can be classified as having MetS. This increased prevalence of MetS is critical as it is associated with a two-fold elevated risk for cardiovascular disease. Although the pathophysiology underlying this increase in disease has not been clearly defined, recent evidence indicates that alterations in the control of coronary blood flow could play an important role. The purpose of this review is to highlight current understanding of the effects of MetS on regulation of coronary blood flow and to outline the potential mechanisms involved. In particular, the role of neurohumoral modulation via sympathetic α-adrenoceptors and the renin-angiotensin-aldosterone system (RAAS) are explored. Alterations in the contribution of end-effector K(+), Ca(2+), and transient receptor potential (TRP) channels are also addressed. Finally, future perspectives and potential therapeutic targeting of the microcirculation in MetS are discussed. This article is part of a Special Issue entitled "Coronary Blood Flow".

Relationship between chronic kidney disease and risk of coronary heart disease in Korean men

There have been many epidemiological researches of chronic kidney disease (CKD), accompanied by an increase in the incidence of coronary heart disease (CHD). However, as far as we know, little research has been done to examine the extent of the relationship between CKD and CHD as estimated by Framingham risk score (FRS) in Korean men. CKD was defined as either proteinuria or an eGFR of < 60 mL/min per 1.73 m(2). The FRS has been used to predict the 10-yr risk of coronary events and usually divided into three levels of risk < 10% (low), 10%-19% (intermediate) and ≥ 20% (high). We defined FRS ≥ 10% as more-than-a-moderate CHD risk group and FRS ≥ 20% as a high CHD risk group, respectively. After adjusting for covariates, multivariable-adjusted logistic regression analyses showed a strong statistical significant relationship between CKD and high risk of CHD (adjusted OR, 1.95 [95% CI, 1.32-2.87]). Dipstick urinalysis and eGFR can be readily measured in most clinical settings. The measurement of kidney function may represent a relatively inexpensive and efficient way to identify individuals at higher risk for CHD.